In a move which has shown how much the competitive landscape has moved in the past decade, Microsoft (MSFT).

Microsoft is still reeling from its own anti-trust settlement in the E.U. just two years ago.  The decade long fight ended with Microsoft creating a browser ballot box in its Windows operating system and having to pay out almost $2.5B in fines.

“The company that was the 800-pound gorilla is now resorting to antitrust, where it is always the case that the also-rans sue the winners,” said Michael A. Cusumano, a professor at the Massachusetts Institute of Technology’s Sloan School of Management who has studied Microsoft to the NYTimes.

Until now, Microsoft has been fighting Google by proxy in the E.U. and in the U.S. by enlisting subsidiaries and partners to file anti-trust actions against its rival.

The complaint is that Google uses its market-leading position in search to block competitors (such as Microsoft) from entering search and other related fields.  Microsoft breaks these down with six examples:

First, in 2006 Google acquired YouTube—and since then it has put in place a growing number of technical measures to restrict competing search engines from properly accessing it from their search results.  Without proper access to YouTube, Bing and other search engines cannot stand with Google on an equal footing in returning search results with links to YouTube videos and that, of course, drives more users away from competitors and to Google.

Second, in 2010 and again more recently, Google blocked Microsoft’s new Windows Phones from operating properly with YouTube. Google has enabled its own Android phones to access YouTube so that users can search for video categories, find favorites, see ratings, and so forth in the rich user interfaces offered by those phones.  It’s done the same thing for the iPhones offered by Apple, which doesn’t offer a competing search service.

Unfortunately, Google has refused to allow Microsoft’s new Windows Phones to access this YouTube metadata in the same way that Android phones and iPhones do.  As a result, Microsoft’s YouTube “app” on Windows Phones is basically just a browser displaying YouTube’s mobile Web site, without the rich functionality offered on competing phones.  Microsoft is ready to release a high quality YouTube app for Windows Phone.  We just need permission to access YouTube in the way that other phones already do, permission Google has refused to provide.

Third, Google is seeking to block access to content owned by book publishers.  This was underscored in federal court in New York last week, in the decision involving Google’s effort to obtain exclusive and unfettered access to the large volume of so-called “orphan books”—books for which no copyright holder can readily be found.  Under Google’s plan only its search engine would be able to return search results from these books.  As the federal court said in rejecting this plan, “Google’s ability to deny competitors the ability to search orphan books would further entrench Google’s market power in the online search market.”  This is an important initial step under U.S. law, but it needs to be reinforced by similar positions in Europe and the rest of the world.

Fourth, Google is even restricting its customers’—namely, advertisers’—access to their own data.  Advertisers input large amounts of data into Google’s ad servers in the course of managing their advertising campaigns.  This data belongs to the advertisers:  it reflects their decisions about their own business.  But Google contractually prohibits advertisers from using their data in an interoperable way with other search advertising platforms, such as Microsoft’s adCenter.

This makes it much more costly for Google’s advertisers to run portions of their campaigns with any competitor, and thus less likely that they will do so.  That is a significant problem because most advertisers figure that they have to advertise first with Google.  If it’s too expensive to port their advertising campaign data to competing advertising platforms, many won’t do it.  Competing search engines are left with less relevant ads, and less revenue.  And while this restraint isn’t visible to consumers, its effects are nonetheless felt across the Web.  Advertising revenue is the economic propellant fueling the billions of dollars needed for ongoing search investments.  By reducing competitors’ ability to attract advertising revenue, this restriction strikes at the heart of a competitive market.

Fifth, this undermining of competition is reflected in concerns that go beyond Google’s control over content.  One of the ways that search engines attract users is through distribution of search boxes through Web sites.  Unfortunately, Google contractually blocks leading Web sites in Europe from distributing competing search boxes.  It is obviously difficult for competing search engines to gain users when nearly every search box is powered by Google.  Google’s exclusivity terms have even blocked Microsoft from distributing its Windows Live services, such as email and online document storage, through European telecommunications companies because these services are monetized through Bing search boxes.

Finally, we share the concerns expressed by many others that Google discriminates against would-be competitors by making it more costly for them to attain prominent placement for their advertisements.  Microsoft has provided the Commission with a considerable body of expert analysis concerning how search engine algorithms work and the competitive significance of promoting or demoting various advertisements.

Google hasn’t formally responded to the charges only saying it hadn’t done anything wrong. Google is also facing anti-trust fears in the U.S., most recently with the Texas Attorney General and over its proposed ITA acquisition.